Apparatus for automatically positioning the rolls in roller-mills in accordance with the material feed



Sept. 28, 1954 F. TANNER 2,690,306

APPARATUS FOR AUTOMATICALLY POSITIONING THE ROLLS IN ROLLER-MILLS INACCORDANCE WITH THE MATERIAL FEED Filed Dec. 27, 1949 5 Sheets-Sheet llwmm l ifz 751men 6?? Sept. 28, 1954 F. TANNER APPARATUS FORAUTOMATICALLY POSITIONING THE ROLLS IN ROLLER-MILLS IN ACCORDANCE WITHTHE MATERIAL FEED Filed Dec. 27, 1949 5 Sheets-Sheet 2 3 Sheets-Sheet 3FRITZ TANNER C. 7. 7 e@ his ATTORNEY Sept. 28, 1954 F. TANNER IAPPARATUS FOR AUTOMATICALLY POSITIONING THE ROLLS IN ROLLER-MILLS INACCORDANCE WITH THE MATERIAL FEED Filed Dec. 27, 1949 TF8 N 8 1 g UN mmm mm mm! mg P P m? i 2 k a @N mm mm P mm! A I m. G NT P 2 I) M WQ A mm Hm N N I\.\|\\ mT W F mm m w m i m \mm M E 8 mm mm, I W C mm m 5 mmPatented Sept. 28, 1954 APPARATUS FOR AUTOMATICALLY POSI- TIONING THEROLLS IN ROLLER-MILLS IN ACCORDANCE WITH THE MATERIAL FEED Fritz Tanner,St. Gallen, Switzerland, assignor to Gebrudcr Buhler, Uzwil, SwitzerlandApplication December 27, 1949, Serial No. 135,239

Claims priority, application Switzerland April 14, 1949 4 Claims. 1

My present invention relates to a starter and regulator for roller millscomprising pressurefluid servomotors for automatically throwing thegrinding rollers and feed rollers in and out of gear, and a devicedisposed in the goods inlet for controlling the pressure-fluid feed tothe servomotors.

The starters and regulators of the type indicated, as known in the artof grinding grain and the like, do not operate quite satisfactorily anddo not quite correspond to practical requirements owing to the fact thatthe grinding rollers are thrown in and out of gear at a comparativelyslow speed.

While in the case of a manually operated starter, the latter is quicklythrown in by the miller through a good pull, and the grinding rollersthrough exerting a blow onto a pawl which looks the engaging lever arequickly released under spring pressure. The automatic throwing in andout of gear is slowed down through the use of a pressure-fluidservomotor.

The said disadvantage of known roller mill starters and regulators ofthe type indicated and further disadvantages which will become apparentto one skilled in the art from the following description of one knownform of starter and regulator, are avoided by virtue of my presentinvention in that a reversing valve is provided in the pressure-fluidsupply pipe of the servomotors, which valve is reversible through thecontroller in order to permit of quickly throwing the grinding rollersand the feed rollers in and out of gear.

The invention will be described in more detail in connection with theaccompanying drawing wherein like characters of reference indicateidentical elements, and wherein Figs. 1 and 2 show two different formsof my present invention in vertical section applied to a known rollermill.

Fig. 3 is a diagrammatic view showing a number of units illustrated inmore detail in Fig. l, with connecting fluid pressure conduits showntherein; and

Fig. 4 is a diagrammatic view similar to that of Fig. 3, illustrating anumber of units of Fig. 2.

Fig. 1 shows a known double roller mill in the casing l of which twopairs of grinding rollers 2, 3 and two pairs of feed rollers 4, 5 aredisposed. The regulating mechanism for the movable grinding roller ofeach roller pair is disposed out side the casing l and laterallythereof. For the sake of clarity, the regulating mechanism associatedwith the right-hand mill side is shown in the drawing on the left-handmill side. The said regulating mechanism comprises a swing bearing forthe movable grinding roller 2, which bearing is engageable through a rod1 provided with a handwheel l. The said rod is pivoted to an engaginglever 8 which is mounted on the coupling shaft 9. Numeral l0 designatesthe disengaging spring acting on the bearing 6. A servomotor piston IIis operatively connected to the lever B and operates in a cylinder I2fixed to casing I. Numeral I3 designates a fixed abutment for lever 8. Ahopper I4 for the goods to be ground is disposed above the feedingrollers 4 and 5 and is closable at the bottom through a feeder segmentl5 disposed above the feeder roller 4. A lever 16 serves for actuatingthe segment l5 and is connected to the piston N3 of a second servomotorthrough a rod H. The piston I8 operates in a cylinder H3 in which isdisposed a spring 24 which acts on the piston l8 so that the lattertends to move the segment I5 to closing position. A pump 23 deliverspressure fluid through piping 25 into the cylinders 12 and I9. The fluidarriving in cylinder [9 tends to depress the piston 58 against theaction of spring 24 and thus to open the segment l5. Such openingaction, however, only takes place when the bore I8 in piston i8 isclosed. When the bore I8 is open, the fluid can return through piston [8to pump 23. A control pin 20 is provided for closing the bore I8 and hasa tip 20' at the bottom, which cooperates with the said bore, While thepin at the top is pivoted to an arm 2| on which is disposed a controller22 for the goods in hopper l4.

In Fig. 1, an auxiliary reversing slide valve is shown, which comprisesa cylinder 26, a piston 21, a spring 28, and seven ports 29-35. The saidvalve for the sake of clarity is shown in a larger scale than the millunit. The said valve, as regards its stroke and diameter, actually issubstantially smaller than the piston l8 associated with feeder segment15. The piston 21 has a relieved portion forming an annular chamber 36.The fluid delivered through the pump 23 flows through line 25 and a widebore 33 into cylinder 25 and thence into the annular chamber 36 ofpiston 21. In the position shown, the fluid is discharged through portBil and flows into cylinder 52. The latter thus communicates directlythrough large-diameter lines with the pump or the central circulatingsystem, and the pressure in cylinder i2 is exactly the same asthroughout the system. The port connecting the main line 25 with thepressure space of cylinder 26, is or" very narrow bore. A further line28, of somewhat larger core, connects cylinder 25 with cylinder H5. Theautomatic regulating system operates in the following manner: When theroller mill is thrown into gear, the pump 23 supplies fluid into mainline 25, under a pressure regulated by means of an overflow valve (notshown) provided between lines 25 and 35, from which valve the pressurefluid returns to the suction port of pump 23 through return line 35. Thecontroller and consequently the tip it of control pin 25 are retained intheir upper position by the action of spring The upper end of bore 53'of piston i3 is fully open and the pressure fluid supplied from themain-line 25 to the branch line through the very narrow port 3 freelyescapes through bore 58. Thus the pressure in the branch line remainslow. The spring maintains piston l 8 in its upper position and holds thesegmental feed-gate in closing position. Piston 2'? is held spring 23 inits lower terminal position. Port lid of cylinder 25 is closed and port3i opened, the main line 25 leading to the servomotor cylinder l2 thusbeing connected to the return line The piston ll of servomotor i2 isretained by action of spring Ill in its left terminal position and thusthe grinding rollers 2, 3 are out or grinding en agement. As soon asgoods are supplied to the rol1er'nill, the pin 28 is depressed by thegoods running into hopper I l and weighting the controller 22, wherebythe bore i8 is closed by the tip 28'. The pressure fluid then depressesthe piston 58 until a passage of such size is created between the tip itof pin 2!? and the upper end of bore it that the fluid can escapethrough said bore. The pin 26 and piston 28 thus always are moved as ifthey were rigidly interconnected. The fluid pressure is defined by thestrength or" spring 2%, the diameter of piston 58 and the position oftip 26, which latter depends on the quantity of goods supplied to theroller mill. Substantially at the same time at which the segmental feedgate I is opened, the piston 2? of the reversing slide valve 26 ispushed to its upper terminal position by the rising pressure below it,thus opening the pressure fluid main line 25 to the servomotor 52. Thelatter then suddenly moves the grinding roller 2 into grindingengagement with the roller 3, the servomotor 22 being connected throughlarge-diameter lines with the pump 23.

The opening of the segmental feed gate i5 is continuously changeddependent upon the quantity of goods supplied to the roller mill, whilethe grinding rollers remain in engagement with each other. As supply ofgoods through the hopper Id ceases he controller 22 permits the spring22' to raise the controller, the lever 2i and the pin 26. The latteruncovers the upper end of bore l8 in piston i3, and like pressures arebuilt up below piston 2i and above piston H8. The magnitude of thispressure here again is defined through the d iameter of piston 53 andthe spring 24 The said elements are so designed that the pressuresufiices to compress the spring 28 of piston Ti and maintain the latterin the position shown. When, however, the pin 25 uncovers a part of boreis in. piston is, the fluid is discharged through said bore at a quickerrate than at which it can be replenished through the narrow port Thespace under piston 2i thus is depressurise spring 28 can depress piston22 to its lower position. Communication between the ports and 33 thus isinterrupted, and communication established between port 31 and dischargeport The fluid thus may flow from cylinder 52 through large-bore linesto pump 23, and stopping is effected very quickly. The piston whi n hasa very small stroke only, never can st 1" still in an intermediateposition, but always will occupy either of the terminal positions atonce so that the ports 33 and 3| in cylinder i1? always fully open.

In Figures 1 and 2, the piston valves 2? are provided with a stop ll toform an annular channel around the same when the piston valve 23: is inits down position. In this lowermost position of the piston valve 2!pressure fluid can flow to the underside of the piston valve 21 from therestricted or smaller conduit 34 into the space low the piston slidevalve 2'1, and building up pressure moves the piston valve 21' againstthe action of the spring 28, to its uppermost position, provided fluidis prevented by the valve from ii-owing through the channel 8%.

Owing to the very narrow bore in port. 35-, the piston 93 of feedersegment l5 moves at a slower speed than when controlled only by the pinSuch slower speed, however, is not a disadvantage, but an advantage,since the goods, e. g. the l -t husk oi the third and fourth groats,does not flow uniformly through the hopper i l past the controller buttends to stick or form bridges and then to give way suddenly. The pistonis of the arrangement shown in Fig. 1 follows up such irregularity onlyslowly and equalizes the same so as to bias the position of feedersegment inconsiderably and so as to maintain uniform feed of the goods.

A further feature of the form of invention shown in Fig. l is that onlya very small tion of the total pump delivery flows throu h narrow port El so that t -e fluid cons for the slow movements of piston 13 withfeeder segment i5 is small, since piston l l for the ing rollers doesnot consume any pressure fluid when engaged.

Finally, the pressure in the cylinders i9 and by suitably selecting thediameter of piston and the spring may be maintained at a lower valuethan in the pump piping 25 or in the central supply system, and thefeeder segments i5 of all the mill units hooked up thus can operateindependently of each other.

In Fig. 3, the respective reference characters are the same as inFigures 1 and 2 for the corresponding parts, except that a further line:Jd from the cylinders is to the pump is shown This conduit 39 is merelyan elongation of e conduit adjacent the cylinder IS in l, or anelongation of the conduit from the check valve 38 to the pump 23, inFigure 2.

In Figures 1 and 2, an overflow valve shown for taking care of anyoverflow pressurthe usual spring therein being correspondi regulated.

While Fig. 3 diagrammatically shows a number of units illustrated inFig. 1, the Fig. 4i is similar diagrammatic illustration of a series ofunits shown in Fig. 2.

In the second form of my present invention shown in Fig. 2, the feedersegment I5 is not regulated through a servomotor l8, 19 but is movedthrough a conventional feeling flap Ma in hopper i l by means of leversl6 and Ida. A slight movement of said flap in its topmost position, i.e. when goods run no more, may be utilized for quickly starting andstopping the grinding and feeding rollers by means of the control slidevalve. For such purpose the line 29 of the latter terminates in a smallcheck valve 38 which in operation is closed through the pressure in line29. When goods run no longer, i. e. when flap Ma; is at the highestelevation, the valve 38 opens and the fluid can quickly flow from line29 back to the pump, since fluid cannot flow so quickly through the verynarrow port 34. The piston 21 thus is lowered and uncovers thelarge-bore port 3| through which the fluid then flows from the cylinderi2 into the return line 35. Piston H thus disengages quickly. When goodsrun again, the operation described is reversed.

By adding, in the form shown in Fig. 1, a stop valve 2lla in the line 2econnecting reversing valve E6, 2'? and regulator I820, the supply offluid to the latter may be interrupted. When said valve 23a is closed,the pressurized fluid, e. g. compressed air, supplied through fine-boreport 34 pushes the piston 21 of the reversing slide valve upwardly, andthe grinding and feeding rollers thus remain in gear, even though thereis only a small quantity of goods left in hopper I d, i. e. when theregulator I32fi would throw the rollers out of gear. It is, however,desirable in such case to let the rollers remain in gear in order thatthe hopper l4 may be completely emptied through the narrow gap betweensegment l5 and roller l, which gap is always present.

When compressed air is used as fluid, all the return lines to the pumpare eliminated. Figs. 1 and 2 for such case show the piping system forthe reversing slide valve in dash-and-dot lines. When, further,connecting a narrow pressure line at 32, fresh compressed air also flowsinto the discharge line 35 when the reversing slide valve is disengaged,i. e. when piston 21 is fully depressed. In such latter case, not onlythe spent air from cylinder i2, which will flow through port El, butalso fresh air flowing through port 32 will be available for actuating asignal device 31. The latter will be heard as long as the piston remainsin its bottommost position, i. e. as long as the mill unit isinoperative. As soon as the unit is put in operation, the signal pipe 31is silenced.

The rod ll of piston l8 of the servomotor also may actuate the speedgoverning means (not shown) of the grinding and feeding rollers, besidesthe feeder segment I5.

When the controller 22 only performs the operation of throwing thegrinding rollers and the feeding rollers in and out of gear, while thesupply of goods (by means of segment 15) is regulated manually ormechanically, the piston [8 of the arrangement shown in Fig. 1 may beblocked in cylinder til, the mode of operation of the reversing organsremaining the same.

in the two forms of invention described with reference to Figs. 1 and 2,a uniform and high pressure is maintained in the servomotors forstarting and stopping the grinding and feeding, and in the supply pipesfor the servomotors. In the servomotors for regulating the supply ofgoods, and in the pressure spaces of the reversing slide valve a lowerpressure prevails. In the case of a central fluid supply to a pluralityof parallel-operating mill units, the said lower pressure may bedifierent for the various units in order to attain a proper operation ofthe units when they encounter different resistances.

What I claim as new, and desire to secure by Letters Patent, is:

1. A system for regulating the grinding gap of a roll pair dependentupon the quantity of material fed thereto, having a pair of grindingrollers, adapted to be put into and out of grinding relation, aservomotor having a cylinder and a piston, means connecting said pistonwith at least one of said rollers, a spring interposed in said means,the tension of said spring being related to the diameter of said piston,a hopper having a wall, a material flow controller in said hopper, apair of feed rollers in the said hopper, and in the path of saidmaterial flow from said hopper wall, and spaced from said wall oneroller above the other, a feeder segment disposed between said hopperwall and said upper feed-roller, means connecting said feeder segmentwith said mate rial controller, said means including fluid pressureoperated means having a cylinder and a valve and a valve stem, saidvalve stem being movable by said fluid pressure and connected with saidcontroller, a pump for said pressure fluid, and a conduit from. saidpump to said grinding roller operating servomotor for placing thegrinding rollers into grinding position, and for supplying the saidvalve cylinder with pressure fluid to operate said feeder segment toopen the material flow to the feeder rolls, and thus to said grindingrollers, the combination of a slide valve mechanism interposed in saidpump conduit leading from said pump to the grinding roller servomotor,said mechanism comprising a cylinder with conduit openings, a pistonslide valve in said cylinder having a hollow interior and an outer circumferential groove, a spring in said valve interior having one endacting against said slide valve, and the other end against saidcylinder, said slide valve being shorter than the interior length ofsaid cylinder, the aforesaid pump conduit supplying fluid to said outercircumferential groove of said slide valve, when said valve is in oneposition, a conduit connecting with the space in said circumferentialgroove and with the conduit to said servomotor cylinder, and arestricted conduit supplying fluid to said slide valve cylinder outsideof said piston slide valve, a conduit guiding said restricted fluid fromsaid slide valve cylinder to the feeder segment cylinder of theaforesaid fluid pressure operated means, a conduit leading off from thepump conduit for supplying the slide valve cylinder with fluid when theslide valve is down, a conduit leading off from the servomotor conduitand to the upper part of the slide valve cylinder when said slide valveis down, and a conduit communicating with the interior of the slidevalve cylinder and with the pump for returning the fluid returning fromsaid servomotor to said pump, whereby the fluid from the pumpunrestrictedly passes through the groove in the slide valve to theservomotor to actuate the piston in the servomotor cylinder to place thegrinding rollers in grinding relation, to obtain a fast grindingengagement, and the fluid return from said servomotor to the pump flowspromptly through unrestricted conduits, enabling the spring at theservomotor to place the grinding roller to ungrinding relationship, thefeed segment opening and closing its space in response to the amount offlow of the material, the restricted fluid flow below the said slidevalve actuating said feeder segment means to open and close said i'eedersegment in respect to said feeder rollers.

2. The structure of claim 1, in which the said fluid pressure operatedmeans is a servomotor in which the piston has a channel from top tobottom of said piston and the valve stem is adapted to open or closesaid channel depending on the position of said material controller.

3. The structure of claim 1, in Which the said fluid pressure operatedmeans has its valve stem resting on a material controller in the form ofa hinged plate, and a lever interposed between said plate and the saidfeeder segment.

4. The structure of claim 1, in which a plurality of such structures areadjacent each other 15 having common conduits to and from said pump.

References Cited in the file of this patent Number Number UNITED STATESPATENTS Name Date Moog Sept. 9, 1930 FOREIGN PATENTS Country Date ItalyJune 18, 1938 Great Britain July 28, 1932 Germany Dec. 11, 1930 GermanyMar. 10, 1939

